1. Field of the Invention
The present invention relates to storage containers. More particularly, the present invention relates to proppant discharge systems wherein proppant can be discharged from the storage container. Additionally, the present invention relates to a process for providing proppant to a well site by the transport and delivery of the proppant containers.
2. Description of Related Art
Hydraulic fracturing is the propagation of fractions in a rock layer caused by the presence of pressurized fluid. Hydraulic fractures may form naturally, in the case of veins or dikes, or may be man-made in order to release petroleum, natural gas, coal seam gas, or other substances for extraction. Fracturing is done from a wellbore drilled into reservoir rock formations. The energy from the injection of a highly-pressurized fracking fluid creates new channels in the rock which can increase the extraction rates and ultimate recovery of fossil fuels. The fracture width is typically maintained after the injection by introducing a proppant into the injected fluid. Proppant is a material, such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped.
With the rise of hydraulic fracturing over the past decade, there is a steep climb in proppant demand. Global supplies are currently tight. The number of proppant suppliers worldwide has increased since 2000 from a handful to well over fifty sand, ceramic proppant and resin-coat producers.
By the far the dominant proppant is silica sand, made up of ancient weathered quartz, the most common mineral in the Earth's continental crust. Unlike common sand, which often feels gritty when rubbed between the fingers, sand used as a proppant tends to roll to the touch as a result of its round, spherical shape and tightly-graded particle distribution. Sand quality is a function of both deposit and processing. Grain size is critical, as any given proppant must reliably fall within certain mesh ranges, subject to downhole conditions and completion design. Generally, coarser proppant allows the higher now capacity due to the larger pore spaces between grains. However, it may break down or crush more readily under stress due to the relatively fewer grain-to-grain contact points to bear the stress often incurred in deep oil- and gas-bearing formations.
Typically, in any hydraulic fracturing operation, a large amount of such proppant is required. Typically, it has been difficult to effectively store the proppant at the fracturing sites. Additionally, it has been found to be rather difficult to effectively transport the proppant to the desired location. Often, proppant is hauled to the desired locations on the back of trucks and is clumped onsite. Under such circumstances, the proppant is often exposed to adverse weather conditions. This will effectively degrade the quality of the proppant during its storage. Additionally, the maintenance of proppant in containers at the hydraulic fracturing site requires a large capital investment in storage facilities. Typically, the unloading of such storage facilities is carried out on a facility-by-facility basis. As such, there is a need to be able to effectively transport the proppant to and store the proppant in a desired location adjacent to the hydraulic fracturing location.
With the development and acceptance of the well stimulation methodology known as “hydraulic fracturing”, a unique logistics challenge has been created in delivering the massive quantities of proppant from domestic sand mines to the wellhead. This logistics challenge affects every stakeholder up-and-down the logistics chain. In particular, this includes sand mine owners, railroads, trans-loading facilities, oil-field service companies, trucking companies and exploration and production companies. The existing method of delivering sand to the consumer requires the use of expensive specialized equipment and a high level of coordination. This makes the process subject to a myriad of problems that disrupt the efficient flow of proppant to the wellhead. The result of utilizing the current method is the expenditure of hundreds of millions of dollars in largely unnecessary logistics costs.
Sand mines are being rapidly developed all over the United States to satisfy the demand that the “Shale Boom” has created for proppant. Most of the recent mines that have come on-line, or are in varying stages of development, have limited transportation infrastructure to support the export of sand from the sand-pit. As a result, many mines are building rail-spurs that will accommodate up to 100 rail cars or more that can be loaded and stand for transportation to the designated destination. Along with rail-track, these companies are also investing in expensive vertical silo storage facilities to store thousands of tons of proppant. The sand mines are unable to effectively ship proppant to the shale regions without equal fluid trans-loading and storage facilities on the receiving end of the logistics chain. This results in lost revenue and productivity for the mine owner and higher prices for proppant buyers in the destination region.
Railroads are a critical part of the logistics chain required to move proppant from mine to the various shale regions. Due to the lack of rail track and trans-loading facilities in some of these remote regions, the railroad companies must be selective of their customers' delivery locations, and make sure that their customers have the ability to efficiently off-load rail cars. Recently, the railroads have seen the allocated fleet of hopper cars being stranded at those destinations where there is no cost-effective storage option to efficiently off-load those cars. Consequently, there has been a significant opportunity cost that the railroads have been forced to pay. As such, a need has developed for facilitating the ability to quickly and inexpensively off-load proppant from rail cars so as to enable the railroads to improve the velocity, turn-around and revenue-generating capacity of the rail-car fleet.
Limited storage at trans-loading facilities has severely limited many of the current facilities' ability to operate efficiently. Most trans-load facilities are forced to off-load rail hopper cars by bringing in trucks (i.e. pneumatics) along the rail siding, and conveying sand directly from rail to truck. This requires an intense coordination effort on the part of the trans-loader as well as the trucking community. Long truck lines are commonplace, and demurrage fees (i.e. waiting time charged by trucking companies) amount to hundreds of millions of dollars nationwide. As such, the trans-loader is not able to fully realize the utilization of conveying and other material handling equipment. The throughput of these trans-loading terminals severely reduces costing of the terminal meaningful revenue.
Additionally, optimal trans-load terminal locations are immobile and not able to move from one area of the shale pay to another. Investors in immobile silo and flat storage facilities can see the utilization and value of those investments tumble. A potential loss of the investment in such immobile silos can often scare investment capital away from these types of future projects so as to further exacerbate the logistics chain problem. As such, a need has developed for a portable, inexpensive storage and delivery solution for proppant that would help revive the capital needed to improve the facilities and maximize the revenue-generating potential of existing and new trans-load and storage facilities.
The lack of efficient trans-load and storage facilities in shale regions have taken a heavy toll on the efficiencies of trucking fleets. While trucking companies have typically charged demurrage fees to compensate for the waiting time and lost productivity, those types of charges are under significant resistance from the customer base. When trucking companies are required to wait in line to be loaded, or wait at a well-site to be unloaded, the number of turns that the equipment can make in a day is severely limited. Rather than turning two or three loads in a single day, the trucks more typically make one trip per day, and very commonly may make one delivery every two or three days, This lack of efficient fleet utilization results in the trucking company having to buy more equipment and hire more drivers to move the same amount of material than would be necessary. As such, it would be desirable to eliminate demurrage charges and to present the opportunity for trucking companies to become more profitable while making smaller investments in equipment.
Service companies (such as fracturing companies) are held captive by the current proppant delivery process. This is the result of inefficient trans-load facilities and pneumatic (bulk) truck deliveries. The service company cannot frac a well if it does not have a supply of proppant. It is widely known that the problems surrounding the efficient delivery of proppant to the well-site is one of the primary challenges to the service companies in successfully completing a frac job. Pressure pumps, coiled tubing and other well stimulation equipment, often site idle due to the lack of required proppant at the well-site, “Screening-Out” or running out of proppant is very common at well locations due to the lack of control over what is happening up-stream in the proppant logistics chain. This results in lower profit margins to the service company. Many small to medium-sized hydraulic fracturing companies have little or no logistics infrastructure. Some have entered the marketplace without much thought to the logistics problems associated with taking delivery of the necessary supplies to complete a well. In doing so, many of these companies have been forced to source material and employ very expensive logistics options in order to survive. This has resulted in above-market pricing in order to complete wells. There is also as risk of losing out on otherwise viable hydraulic fracturing contracts. As such, there is a need to lower costs across the board in order to properly compete.
Exploration and production companies, along with the entire U.S. population, pay the ultimate bill for all of the inefficiencies and waste that plagues the proppant supply chain. Service companies are forced to price hydraulic fracturing services by taking into account the historical costs of supply chain problems. Exploration and production companies need to pass on the overall increased cost of production. As such, there is a need to provide a cost-effective solution to improve the profitability of stake holders in the proppant logistics chain, while lowering the overall cost to the consumer.
U.S. patent application Ser. No. 13/427,140, filed on Mar. 22, 2012 by the present inventor, describes a system for the delivery of proppant between a loading station and the well site. This application describes the steps of placing the storage container in a location adjacent to a train site such that the proppant, as delivered by the train, can be discharged into the container. The container can then be transported for storage in stacks at the loading area or can be delivered to a tilting mechanism at the loading station. The tilting station will tilt the container so as to allow the proppant to flow outwardly therefrom. This proppant will flow, by a conveyor, to a pneumatic truck. The truck can then transport the proppant over the highways to the well site. At the well site, the proppant from the pneumatic truck can then be discharged into a twenty foot container at the well site. These twenty foot containers can be stored at the well site in a stacked configuration. Ultimately, each of the containers can be transported to another tilting mechanism at the well site so that the proppant within each of the storage containers can be discharged onto a conveyor and ultimately for use during the fracturing operation.
In this U.S. patent application Ser. No. 13/427,140, the twenty-foot ISO container that is utilized is one of the most inexpensive and readily-available pieces of transportation equipment in the world. It was determined that the use of the twenty-foot container allows for the transportation of proppant through various minor modifications to the internal walls and reinforcements of the twenty-foot ISO container. The available capacity is more than acceptable. It was determined that this modified twenty-foot container could hold in excess of forty-five tons of proppant. The cost of an unmodified twenty-foot ISO container is less than four thousand dollars. This makes it very affordable compared to the cost of building, vertical silos or flat storage buildings.
The twenty-foot ISO container was modified by cutting a hole in the top of the container and constructing a water-tight, hinged hatch through which the proppant could be poured by any number of readily-available conveying units. There was also a lower hatch in the twenty-foot ISO container. This lower hatch could be opened to drain the proppant out of the twenty-foot ISO container. Alternatively, a square flow-gate was fabricated and welded to the vertical rear lower side of the twenty-foot container. This gate hatch allowed the container to be tilted in the manner of a dump truck bed. As a result, sand could flow out of the flow gate while moderating the flow of the sand.
This patent application provided the ability to trans-load sand via containers from a standard rail hopper car to the twenty-foot ISO container. It was determined that the container could be loaded in less than twenty minutes with at least fort-five tons of proppant. By pre-positioning the container along, the rail track, movable conveyors could work the train from one end to the other and unload the train in a very efficient and timely manner. This part of the process eliminated the coordination efforts of calling in pneumatic trucks that could be systematically loaded by conveying units. This reduced the time necessary to unload a train's hopper cars by many hours. It also eliminated truck traffic and demurrage charges at the rail-spur and trans-load facility.
Once the proppant is loaded into the container, another piece of specialized equipment would be used to lift the full container and to stack the container upon other containers. The stackable arrangement of containers allows the ability to operate and store proppant within a very small footprint. The specialized equipment that was required to lift the full containers was so heavy and large that it would have to be disassembled into several pieces before moving from one location to another. This created some limitations on the flexibility that such equipment lent to the containerized process.
By “containerizing” proppant, it was found that an inventory management system could be added in order to provide real-time, accurate information pertaining to the volume/inventory of proppant that the customers own in a particular region. Currently, many proppant buyers are subject to inaccurate volume reporting from trans-loading facilities. As such, they May not be certain that the proppant being delivered to the well-site is, in fact, of the quality and grade that they have purchased. By applying an inventory management system, bar coding, and scanning the containers into and out of inventory, the customers would be assured that they have received, their proppant and would be able streamline the procurement process when ordering more material.
In this prior process, since the twenty-foot ISO container needed to be emptied and trans-loaded into pneumatic trailers for delivery to the wellhead, a tilting unit was incorporated into the process. This tilting unit accepted the twenty-foot ISO containers. The tilting unit is able to lift one end of the container and create the required angle to wholly empty the container through the flow gate. Once tilted, the sand would spill onto the belt of the conveyor and rise vertically into a hopper. The hopper rested on a steel fabrication stand. This stand is high enough such that a truck that pulls a pneumatic trailer could drive under the stand and be gravity fed by the hopper so as to fill up the sand trailer. These “loading stations” could be replicated along a path so as to alleviate the bottleneck of trucks at a trans-load facility that has a limited number of conveyors available to load the trucks. Once again, trucking demurrage at this trans-load facility could be dramatically reduced through the process. The railcars can be off-loaded rapidly and released back to the railroads. This also reduced or eliminated demurrage fees charged by the railroads for rail hopper cars that stood waiting to be off-loaded.
This prior process created an inexpensive storage solution, improved the efficiencies of the trans-loading process, added inventory visibility and controls, and reduced both truck and rail demurrage charges. However, it did have several limitations. For example, the twenty-foot ISO container, while capable of handling ninety thousand pounds of proppant, could not be transported legally over a public road. In most states, the maximum allowable total weight of a vehicle and its payload is eighty thousand pounds of gross vehicle weight in order to be considered a legal load. By law, any load that can be broken down by two units or more, in order to achieve a legal weight limit, must be divided into multiple loads. Since proppant is divisible, the law does not allow for heavy or over-weight loads.
The angle of repose of a granular material is the steepest angle of descent or dip of the slope relative to the horizontal plane when material on the slope face is on the verge of sliding. When bulk granular materials are poured onto a horizontal surface, a conical pile will form. The internal angle between the surface of the pile and the horizontal surface is known as the angle of repose and is related to the density, surface area and shape of the particles, and the coefficient of friction of the material. The angle of repose is also gravity-dependent.
When analyzing the angle of repose of proppant poured into a twenty-foot ISO container, it was evident that much of the volume of such a container was void. Specifically, the upper ends of twenty-foot ISO container could not be utilized without somehow manipulating or tilting the container as it was filled by a conveyor. Moreover, when emptying the container, by way of the original bottom hatch, the proppant would pour directly out of the bottom and leave a significant amount of material sitting on the floor of the container.
U.S. patent application Ser. No. 13/555,635, filed on Jul. 23, 2012 by the present inventor, is the parent of the present application. U.S. patent application Ser. No. 13/555,635 described a new generation of the container by taking the original twenty-foot ISO container and splitting it in half. As such, a ten foot ISO container was provided. By breaking the container into a ten foot configuration, it was determined that such a container could hold approximately 45,000-48,000 pounds of proppant. The total gross vehicle weight of such a fully-loaded container could be legally transported over a public road. This was a major breakthrough. The container could be delivered to the wellhead in advance of a frac crew and eliminate sand deliveries during the fracturing process. Because all of the required proppant for any frac job could be delivered and stored on-site, such a ten-foot ISO container effectively eliminated the occurrence of trucking demurrage charges at the well-site. Also, the use of such a ten-foot container effectively eliminated the problems caused by the angle of repose of the proppant and allowed the volumetric capacity of such a ten-foot ISO container to be more fully utilized. It was found to be the optimal configuration, size, and cost for the process.
This prior application utilized an insert that is fabricated, and welded within the interior of the ten-foot ISO container. The insert allowed, the proppant, loaded through the top hatch, to fully flow out of a newly designed bottom flow-gate. The need to manipulate or tilt the container was eliminated. This ten-foot container could now be filled and emptied by using only gravity to do so.
In the past, various patents have issued relating to storage and transport facilities. For example, U.S. Patent Publication No. 2008/0179054, published on Jul. 31, 2008 to McGough et al., shows a bulk material storage and transportation system. In particular, the storage system is mounted on the trailer of a truck. The storage system includes walls that define an interior volume suitable for receiving the aggregate material therein. There are hoppers provided at the bottom of the container. These hoppers have inclined walls. The hoppers can extend so as to allow the material from the inside of the container to be properly conveyed to a location exterior of the container. Actuators are used so as to expand and collapse the container.
U.S. Pat. No. 7,240,681, issued on Jul. 10, 2007 to L. Saik, describes a trailer-mounted mobile apparatus for dewatering and recovering formation sand. The trailer is mounted to a truck-towable trailer so as to receive sand therein. The container has a pair of sloping end walls. The back end of the container is suitably openable so as to allow the sand to be removed therefrom. A pneumatic or hydraulic ram is provided on the forward part of the container so as to allow the container to be lifted angularly upwardly so as to allow sand to be discharged through the gate at the rear of the container.
U.S. Pat. No. 4,247,228, issued on Jan. 27, 1981 to Gray et al., describes a dump truck or trailer with a pneumatic conveyor. The container is mounted to a frame on wheels. A hydraulic ram tilts the container for dumping through a rear outlet. A pneumatic conveyor is carried by the frame with an intake at the rear of the container. A gate allows the solids to be dumped conventionally by gravity or to be blown to a storage facility by the pneumatic container. The container has a top hatch formed therein so as to allow the solids to be introduced into the interior of the container.
U.S. Pat. No. 2,865,521, issued on Dec. 23, 1958 to Fisher et al., shows a bulk material truck that has an interior volume suitable for the receipt of bulk material therein. A pneumatic conveyer is utilized so as to allow the removal of such material from the bottom of the container. A pair of sloping walls are provided on opposite sides of the container so as to allow the bulk material within the container to be passed toward the bottom of the container. A top hatch is provided on the top of the conveyer. The pneumatic conveyer is connected to the bottom of the container.
It is an object of the present invention to provide a proppant storage container that allows proppant to be easily transported and stored.
It is another object of the present invention to provide a proppant storage container that allows the proppant to be easily and efficiently discharged to the bottom of the container.
It is another object of the present invention to provide a proppant storage container which allows for the effective storage of proppant at the fracturing site.
It is another object of the present invention to provide a process for delivering proppants that eliminates the use of pneumatic trailers.
It is further object of the present invention to provide a proppant storage container and a process for delivering proppant in which of the containers can be moved by a simple forklift.
It is another object of the present invention to provide a process for delivering proppants which effectively eliminates demurrage associated with the loading station and at the well site.
It is a further object of the present invention to provide a process of the deliver proppant which avoids the degradation of the proppant as a result of repeated handling.
It is a further object of the present invention to provide a proppant discharge system which provides a premeasured amount of proppant to the drill site.
It is still another object of the present invention to provide a proppant container which satisfies highway regulation and which has less void space within the interior of the container.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.